Ceramic steel and method of preparing the same

ABSTRACT

A ceramic steel, which is composed of a ceramic phase and a metal phase. The ceramic phase is the boride consisted of one or more elements of Fe, Co, Ni, and one or more metal elements of IVB, VB and VIB of the fourth, fifth and sixth periodic metals. And the metal phase is an alloy composed of Mo and one or more metal elements of Fe, Co, Ni. The ceramic steel has properties of high hardness, excellent wear resistance, corrosion resistance, high temperature resistance, and has good weldability with steel and other metal materials. The ceramic steel can be used for producing knives, cutting tools, and all kinds of wear resistant, corrosion resistant, high temperature resistant materials and all kinds of structural components.

FIELD OF THE INVENTION

The invention belongs to the technical field of composites, in particular to ceramic steel and method of preparing the same.

BACKGROUND OF THE INVENTION

Under the development of social technology and the increase of people's living standards, people's demands for daily supplies are increasing. People put higher request forward aspects such as appearance of products, which is not limited to their qualities and functionalities. Knives, cutting tools, as one of the necessary equipment of kitchen, are perennially in the water, water vapor, salt, acid and other environment, this is a big challenge for corrosion resistance of materials; meanwhile, knives, cutting tools are used for cutting or cutting food, hence, the demand for strength and hardness of materials are increasing.

At present, the common materials used for manufacturing knives and cutting tools on the market are usually those materials such as stainless steel, ceramics and so on. Stainless steel is well accepted due to its properties such as high toughness and corrosion resistance since the advent of it in 1913, which lays a foundation of the development of modern industry and improvement of technology. Therefore, it plays an important role in the production of knives and cutting tools. However, the blade is easy to be blunt and not sharp during use due to its low hardness, poor wear resistance, stainless steel usually needs frequent grinding. Zirconium ceramic knife and cutting tool is one of the new knives and cutting tools developed in recent years, which have properties of high hardness, wear resistance and high temperature resistance. But zirconium ceramic knife and cutting tool have some fatal flaws: High brittleness, poor impact resistance, thin edge of knife and cutting tool, easily chipping during use, which affects the useful life of zirconium ceramic knives and cutting tools. Therefore, in order to better meet people's daily needs, the researchers are keen to research a kind of composite materials which have properties of high hardness, excellent wear resistance, corrosion resistance and high temperature resistance.

SUMMARY OF THE INVENTION

Given the above cited technical problems to be solved, this invention intends to provide ceramic steel, which has properties of high hardness, excellent wear resistance, corrosion resistance, high temperature resistance and good toughness, and method of preparing the same.

Means for solving the technical problems by the invention is aimed to provide ceramic steel. Said ceramic steel in this invention are composed of ceramic phase and metal phase. The ceramic phase is the boride consisted of Fe, Co, Ni, and one or more metal elements of IVB, VB and VIB of the fourth, fifth and sixth periodic metals. And said metal phase is an alloy composed of Mo and one or more metal elements of Fe, Co, Ni.

Preferably, the ceramic steel further contain a few additives, the additives are C and one or more elements of V, Cr, Mn, and Cu.

Preferably, of the ceramic steel, the weight percentage of each chemical component is: B 5˜10 wt. %, Ti 0˜50 wt. %, V 0˜50 wt. %, Cr 0˜50 wt. %, Zr 0˜50 wt. %, Nb 0˜50 wt. %, Mo 20˜60 wt. %, Fe 10˜40 wt. %, Ni 0˜15 wt. %, Co 0˜20 wt. %. Element contents in the additives are no more than 5 wt. %.

Means for solving the other technical problems by the invention is to provide a preparation method of ceramic steel, characterized in that: the preparation method of ceramic steel comprises the following steps of:

After exactly weighing raw materials powder (ceramic phase and metal phase raw materials), mixtures were processed by wet-ball-milled by one of cemented carbide ball, stainless steel ball and corundum ball, with milling media for 20˜100 h, 2˜6 wt. % of forming agent were added, the ball-to-powder mass ratio was (3-10):1;

Mixed slurries were dried, sieved through 200 to 400 mesh, and then compressed under a pressure of 100˜400 MPa.

The blanks were prepared after sintering at 1200˜1500° C. Then, the ceramic steel were obtained.

Preferably, the milling medium described above is one of the following materials: anhydrous ethanol, gasoline, acetone, hexane, carbon tetrachloride and benzene.

Preferably, the forming agent described above is one of the following materials: paraffin composed of n-alkanes, zinc stearate, polyvinyl butyral anhydrous ethanol solution and rubber oil solution.

Preferably, the drying method described above is one of the following methods: vacuum drying, vapor drying and spray drying.

Preferably, the sintering described above is one of the vacuum sintering, hot isostatic pressing sintering, activated sintering and spark plasma sintering.

In comparison with prior art, the ceramic steel in this invention are composed of ceramic phase and metal phase. Ceramic phase is the boride consisted of Fe, Co, Ni, and one or more metal elements of IVB, VB and VIB of the fourth, fifth and sixth periodic metals. Metal phase is an alloy composed of Mo and one or more metal elements of Fe, Co, Ni. Ceramic steel in this invention have properties of high hardness, excellent wear resistance, corrosion resistance and high temperature resistance and can be used for producing knives, cutting tools, and all kinds of wear resistant, corrosion resistant, high temperature resistant materials and all kinds of structural components composed of them. Moreover, ceramic steel have good weldability with steel and other metal materials, which can meet people's daily needs and application in industry, agriculture, machining and medical apparatus and instruments and so on. Moreover, the invention provides a method for preparing ceramic steel.

The raw material reacted during sintering, boride and multiple boride were produced by in situ, which provides high hardness for ceramic steel using the above preparation method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the microstructure of ceramic steel observed under a scanning electron microscope.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The present invention is further described with specific embodiments and tables as below, which will further clarify the aims, technical concept and advantages of this invention. It should be understood that the specific embodiment described above should only be used to explain the present invention, and not to limit it.

Ceramic phase of the ceramic steel is the boride consisted of Fe, Co, Ni, and one or more metal elements of IVB, VB and VIB of the fourth, fifth and sixth periodic metals. Metal phase is an alloy composed of Mo and one or more metal elements of Fe, Co, Ni.

The ceramic steel further contain a few additives, the additives are C and one or more elements of V, Cr, Mn, Cu.

Alloy powders, compound powders and elementary powders can be selected as raw materials to prepare ceramic steel. After exactly weighing raw materials powder (ceramic phase and metal phase raw materials), mixtures were processed by wet-ball-milled by one of cemented carbide ball, stainless steel ball and corundum ball, with milling media for 20˜100 h, 2˜6 wt. % of forming agent were added, the ball-to-powder mass ratio was (3-10):1;

Mixed slurries were dried, sieved through 200 to 400 mesh, and then compressed under a pressure of 100˜400 MPa.

Blanks were prepared after sintering at 1200˜1500° C. Then, the ceramic steel were obtained.

The raw material reacted during sintering, boride and multiple boride were produced by in situ, which provides high hardness for ceramic steel using the above preparation method. The ceramic phase and metal phase precipitated in situ have high bonding strength, so the ceramic steel had high toughness. Therefore, the ceramic steel has excellent mechanical properties.

The hardness of the ceramic steel in the present invention can be up to 50˜75 HRC, comparable to zirconium ceramic, while flexural strength can be up to 1200˜2300 MPa, much higher than zirconium ceramic. In comparison with the widely used stainless steel, ceramic steel has higher hardness, more than doubled wear resistance. Moreover, ceramic steel has excellent chemical stability. Therefore, ceramic steel is suitable for preparing knives, cutting tools, and all kinds of wear resistant, corrosion resistant, high temperature resistant materials and all kinds of structural components composed of them, which are supposed to be used perennially in the water, water vapor, salt, acid, alkali and other work environment. Moreover, ceramic steel has good weldability with steel, hence, it is possible to prepare ceramic steel knives, cutting tools and all kinds of wear resistant, corrosion resistant, high temperature resistant materials and all kinds of structural components composed of them at low costs and easier to achieve large-scale promotion with only a few ceramic steel welding to the stainless steel.

Ceramic steel of this invention have properties of high hardness, excellent wear resistance, corrosion resistance and high temperature resistance and can be used for producing knives, cutting tools, and all kinds of wear resistant, corrosion resistant, high temperature resistant materials and all kinds of structural components composed of them. Moreover, ceramic steel have good weldability with steel and other metal materials, which can meet people's daily needs, and are suitable for application in industry, agriculture, machining and medical apparatus and instruments and so on.

Ceramic steel in this invention are composed of ceramic phase and metal phase. Ceramic phase is the boride consisted of Fe, Co, Ni, and one or more metal elements of IVB, VB and VIB of the fourth, fifth and sixth periodic metals. Metal phase is an alloy composed of Mo and one or more metal elements of Fe, Co, Ni.

Alloy powders, compound powders and elementary powders can be selected as raw materials to prepare ceramic steel. After exactly weighing raw materials powder, mixtures were processed by ball milling, drying, sieving, pressing and sintering. Then, ceramic steel were obtained.

Knives and cutting tools made of ceramic steel have the advantages of stainless steel knives and cutting tools and zirconium ceramic knives and cutting tools without their shortcomings. Therefore, ceramic steel knives and cutting tools can be used to replace existing stainless steel knives and cutting tools and zirconium ceramic knives and cutting tools, which are not only durable, but also cost-effective and easy to realize promotion in application on a large scale.

The specific embodiments and tables described below will further clarify the technical concept of this invention:

EXAMPLE 1

A preparation method of ceramic steel: 20 wt. % of NiB, 40 wt. % of Mo, 5 wt. % of Cr, 10 wt. % of Ni, 1 wt. % of C and Fe powder (the balance), and 2.5 wt. % of paraffin were wet-milled in a ball milling machine for 100 h. The cemented carbide ball-to-powder: (NiB, Mo, Cr, Ni, C and Fe powder) mass ratio was 8:1, anhydrous ethanol were added as milling media. The slurry mixtures were vacuum dried for 7 h at the temperature of 70° C., sieved through 325 mesh, and then compressed. Finally, ceramic steel were obtained after vacuum sintering at 1220° C. for 15 h.

EXAMPLE 2

A preparation method of ceramic steel: 20 wt. % of FeB, 60 wt. % of Mo, 5 wt. % of Cr, 10 wt. % of Ni, 1 wt. % of C and Fe powder (the balance), and 2.2 wt. % of paraffin were wet-milled in a ball milling machine for 85 h. The cemented carbide ball-to-powder: (FeB, Mo, Cr, Ni, C and Fe powder) mass ratio was 6:1, acetone were added as milling media. The slurry mixtures were vacuum dried for 6 h at the temperature of 80° C., sieved through 325 mesh, and then compressed. Finally, ceramic steel were obtained after vacuum sintering at 1250° C. for 14 h.

EXAMPLE 3

A preparation method of ceramic steel: 20 wt. % of CoB, 40 wt. % of W, 20 wt. % of Co, 10 wt. % of Ni, 1 wt. % of C and Fe powder (the balance), and 2 wt. % of rubber oil solution were wet-milled in a ball milling machine for 65 h. The stainless steel ball-to-powder: (CoB, W, Co, Ni, C and Fe powder) mass ratio was 5:1, hexane were added as milling media. The slurry mixtures were vacuum dried for 10 h at the temperature of 60° C., sieved through 300 mesh, and then compressed. Finally, ceramic steel were obtained after hot isostatic pressing sintering at 1280° C. for 12 h.

EXAMPLE 4

A preparation method of ceramic steel: 50 wt. % of TiB₂, 20 wt. % of Mo, 5 wt. % of Cr, 15 wt. % of Ni, 1 wt. % of C and Fe powder (the balance), and 2.5 wt. % of rubber oil solution were wet-milled in a ball milling machine for 80 h. The stainless steel ball-to-powder: (TiB₂, Mo, Cr, Ni, C and Fe powder) mass ratio was 3:1, carbon tetrachloride were added as milling media. The slurry mixtures were spray dried for 8 h at the temperature of 90° C., sieved through 200 mesh, and then compressed. Finally, ceramic steel were obtained after hot isostatic pressing sintering at 1300° C. for 12 h.

EXAMPLE 5

A preparation method of ceramic steel: 50 wt. % of ZrB₂, 20 wt. % of Mo, 5 wt. % of Cr, 15 wt. % of Ni, 1 wt. % of C and Fe powder (the balance), and 3 wt. % of zinc stearate were wet-milled in a ball milling machine for 90 h. The corundum ball-to-powder: (ZrB₂, Mo, Cr, Ni, C and Fe powder) mass ratio was 5:1, benzene were added as milling media. The slurry mixtures were spray dried for 5 h at the temperature of 70° C., sieved through 400 mesh, and then compressed. Finally, ceramic steel were obtained after spark plasma sintering at 1280° C. for 2 h.

EXAMPLE 6

A preparation method of ceramic steel: 50 wt. % of NbB₂, 20 wt. % of Mo, 5 wt. % of Cr, 15 wt. % of Ni, 1 wt. % of C and Fe powder (the balance), and 3 wt. % of polyvinyl butyral anhydrous ethanol solution were wet-milled in a ball milling machine for 75 h. The corundum ball-to-powder: (NbB₂, Mo, Cr, Ni, C and Fe powder) mass ratio was 5:1, gasoline were added as milling media. The slurry mixtures were vapor dried for 8 h at the temperature of 90° C., sieved through 400 mesh, and then compressed. Finally, ceramic steel were obtained after activated sintering at 1250° C. for 15 h.

EXAMPLE 7

A preparation method of ceramic steel: 25 wt. % of FeB, 35 wt. % of Mo, 10 wt. % of Cr, 5 wt. % of Ni, 0.6 wt. % of C, 2 wt. % of V, 5 wt. % of Cu and Fe powder (the balance), and 3 wt. % of paraffin were wet-milled in a ball milling machine for 60 h. The corundum ball-to-powder: (FeB, Mo, Cr, Ni, C, V, Cu and Fe powder) mass ratio was 6:1, gasoline were added as milling media. The slurry mixtures were vacuum dried for 8 h at the temperature of 90° C., sieved through 400 mesh, and then compressed. Finally, ceramic steel were obtained after activated sintering at 1300° C. for 15 h.

TABLE 1 Hardness and Flexural Strength of Ceramic Steel Example Hardness (HRC) Flexural Strength (MPa) 1 65 2017 2 68 2278 3 67 1882 4 72 1635 5 75 1340 6 71 1390 7 70 1720

The above mentioned description applies solely to the ideal embodiment as offered by preparation methods of ceramic steel, and should not serve to restrict its application. Any amendments, equivalent substitutions and improvements that are implemented in the scope of spirit and principles of ceramic steel will be protected by this invention document. 

1. A ceramic steel, wherein: said ceramic steel comprises a ceramic phase and a metal phase, said ceramic phase is a boride comprising one or more elements of Fe, Co, Ni, and one or more elements of IVB, VB and VIB periodic metals; said metal phase is an alloy composed of Mo and one or more metal elements of Fe, Co, Ni.
 2. The ceramic steel according to claim 1, wherein said ceramic steel further comprises an additive comprising C and at least one of V, Cr, Mn, and Cu.
 3. The ceramic steel according to claim 1 wherein the weight percentage of each chemical element of said ceramic steel is: B 5˜10 wt. %, Ti 0˜50 wt. %, V 0˜50 wt. %, Cr 0˜50 wt. %, Zr 0˜50 wt. %, Nb 0˜50 wt. %, Mo 20˜60 wt. %, Fe 10˜40 wt. %, Ni 0˜15 wt. %, Co 0˜20 wt. %, and each of the elements in said additive is no more than 5 wt. % based on the total weight of each element in the ceramic steel.
 4. A method for producing a knife, a cutting tool, a wear resistant, corrosion resistant, high temperature resistant material, or a structural component comprising the wear resistant, corrosion resistant, high temperature resistant material, comprising using the ceramic steel according to claim 1 as a starting material. 